Method for providing a corrugated seal in an elastic fluid machine

ABSTRACT

A turbine rotor blade path seal consists of a corrugated strip of sheet metal secured edgewise in an annular groove in the turbine cylinder or casing. The corrugated seal strip requires no edge rolling for the various diameters of the different stages of a multi-stage turbine. Thus, one pattern of a seal strip which is easily customized and assembled can be utilized for all stages of a turbine. The seal strip is caulked or interlocked in the groove at assembly by means of a special tool.

United States Patent [151 3,694,882 Desmond [4 1 Oct. 3, 1972 [54]METHOD FOR PROVIDING A 940,802 11/1909 Green ..415/172 CORRUGATED SEALIN AN ELASTIC 1,424,242 8/1922 Flanders ..415/174 FLUID MACHINEInventor: John William Desmond, Media, Pa.

Assignees: Westinghouse Electric Corporation; Pittsburgh ElectricCorporation, Pittsburgh, Pa.

Filed: Sept. 24, 1970 Appl. No.1 75,194

US. Cl. ..29/ 156.8 R, 29/DIG. 34, 277/ l .277/53, 277/96, 415/172,415/174 Int. Cl. ..B2lk 3/04 Field of Search...29/l56.8 R, DIG. 34;415/174, 415/171, 172; 277/53, 96,1

References Cited UNITED STATES PATENTS Comery ..277/53 PrimaryExaminer-John F. Campbell Assistant Examiner-Donald C. Reiley, IllAttorney-A. T. Stratton, F. P. Lyle, F. Cristiano, Jr. and F. J. Baehr,Jr.

ABSTRACT A turbine rotor .blade path seal consists of a corrugated stripof sheet metal secured edgewise in an annular groove in the turbinecylinder or casing. The corrugated seal strip requires no edge rollingfor the various diameters of the different stages of a multistageturbine. Thus, one pattern of a seal strip which is easily customizedand assembled can be utilized for all stages of a turbine. The sealstrip is caulked or interlocked in the groove at assembly by means of aspecial tool.

6 Claims, 7 Drawing Figures PATENTEBIIBT 3 I972 SHEET 2 OF 2 FIG. 3.

METHOD FOR PROVIDING A CORRUGATED SEAL IN AN ELASTIC FLUID MACHINEBACKGROUND or THE INVENTION This invention relates, generally, toelastic fluid machines and, more particularly, to rotor blade path sealsfor axial flow turbines.

In order to control leakage of the motive fluid past the rotor blades ofa multi-stage axial flow turbine, it is desirable to provide a sealaround each row of blades in the space between the outside diameter ofthe blades and the inside diameter of the turbine cylinder or casing.l-leretofore, it has been necessary to manufacture seal members havingdifferent curvatures for each stage, since the diameters are differentfor each stage of a multi-stage turbine. This invention provides a sealmember which can be utilized for all stages of a turbine and does notrequire special forming equipment at the assembly area either in theshop or in the field.

SUMMARY OF THE INVENTION In accordance with one embodiment of theinvention, a corrugated strip of sheet metal is secured edgewise in anannular groove in a turbine casing to provide an annular seal striparound a row of rotor blades. The corrugated strip is initiallyrectilinear, but easily conforms to the' curvature of the casing when itis installed and requires no edge rolling for the various diameters ofdifferent stages. The strip is secured in the cylinder by peening orcaulking it in the groove by means of an assembly tool. The sealingaction of the corrugated strip is accomplished by having the end of thestrip in full contact with the bottom of the groove.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of thenature of the invention, reference may be had to the following detaileddescription, taken in conjunction with the accompanying drawing, inwhich:

FIG. 1 is a view, in elevation, of a portion of an axial flow turbinehaving a rotor blade path seal constructed in accordance with principlesof the invention;

FIG. 2 is a view, in section, taken along the line Il-II of FIG. 1;

FIG. 3 is a view, in plan, of a portion of a seal strip employed in FIG.1;

FIG. 4 is a view, in elevation, of the seal strip shown in FIG. 3;

FIG. 5 is a view, partly in elevation and partly in section, showing themanner of utilizing an assembly tool to install the seal strip;

FIG. 6 is an enlarged detail view of the lower portion of the assemblytool and the seal strip; and

FIG. 7 is an isometric view showing a portion of the seal stripinstalled in the turbine cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENT may be secured to arcuate shroudsegments 16 leaving an annular clearance space 18 between the casing 12and the shroud 16 as shown in FIG. 2. v

In order to restrict the flow of the elastic motive fluid around therotor blades, an annular seal 20 is provided in the space 18. As shown,the seal 20 is a corrugated strip of sheet metal secured edgewise, in anannular groove 22 provided in the casing 12 and encircling the annularrow of rotor blades 14. A major portion of the seal strip extends beyondthe casing 12 towards the rotor blades.

As shown more clearly in FIG. I, the corrugation impart flexibilitytothe seal strip 20 and permit it to conform to the curvature of thecasing 12 when the strip is inserted edgewise into the groove 22. Thus,no edge rolling of the seal strip is required for the various diametersof different stages in a multi-stage turbine. The corrugations permitedge forming during normal assembly without using edge rollingequipment.

. In accordance with the usual practice, the turbine casing 12 isdivided into an upper half and a lower half bolted together athorizontal joints 24. Thus, the seal 20 may be made in two halves, eachhalf being of suff cient length to reach from one horizontal joint tothe other when installed in the groove 22.

As shown more clearly in FIG. 2, the seal 20 'is disposed transverselyof the direction of flow of the" As shown more clearly in FIG. 3, theheight of the corrugations of the seal strip 20 is such that the stripfits snugly into the groove 22. Each ridge has a flat surface 28 whichcontacts a side of the groove'22 and a ligament 29 disposed between theflat surfaces 28 at an oblique angle with respect to the surfaces 28, toallow the corrugated strip todeform to accommodate the insertion of thecorrugated strip tightly inthe groove 22, thereby preventing leakage ofthe motive fluid through the groove.

The seal strip 20 may be installed and secured in the groove 22 by meansof an assembly tool 30 shown in FIG. 5. The tool 30 comprises a peeningor caulking member 32 movably disposed inside an inner sleeve 34 whichis movably disposed inside an outer sleeve 36, a compression spring 38surrounding the sleeve 34 between the lower end of the sleeve 36 and aflange 40 on the sleeve 34, and a wedge 42 disposed at the lower end ofthe caulking member 32. The members of the tool are retained together bymeans of a pin 44 secured in the sleeve 36 and extending throughelongated slots 46 and 48 in the sleeve 34 and the member 32,respectively.

As shown more clearly in FIG. 6, the wedge 42 is movably attached to thecaulking member 32 by two plates 50 secured to opposite sides of thewedge and a pin 52 secured in the member 32 and extending into openings54 in the plates 50 which extend a short distance along opposite sidesof the member 32. The.

openings 54 are of such a size that limited movement of the member 32relative to the wedge 42 is permitted.

As shown in FIGS. 5 and 6, when the tool 30 is held on the corrugatedstrip 20 with the member 32 extending between corrugations and a cuttingprojection 56 at the lower end of the member 32 facing a flat surface 28of the strip and pressure is applied on the sleeve 36 to compress thespring 38, the upper end of the member 32 may be struck with a hammer tocause the projection 56 to cut and force a projection 58 from the flatsurface 28 of the strip into a sidewall of the groove 22 in the cylinder12. When the upper end of the member 32 is struck with the hammer thebottom end strikes the sloping surface 60 of the wedge 42, therebycausing the projection 56 to drive the projection 58 into the side wallof the groove. During this caulking operation the pressure of the spring38 on the sleeve 34 is held on the corrugated strip 20 assures that thestrip is fully inserted into the groove 22. When pressure on the sleeve36 is released, the tool 30 can be withdrawn and then utilized to caulkor interlock the seal strip at another point as shown in FIG. 7. Theseal strip may be interlocked at any desired number of points.

A commercial benefit of this invention is that the seal strip can bereplaced in the turbine in the field quickly and economically, therebyavoiding the delay required to return the turbine to the factory. Theflexible corrugated seal permits the seal strip sections to be shippedand handled conveniently as straight, i.e., rectilinear, sections.

From the foregoing description it is apparent that the inventionprovides a turbine rotor blade path seal member which can beeconomically manufactured and installed. The seal member can be utilizedfor all stages of a multi-stage turbine and does not require specialforming equipment at the assembly area.

I claim as my invention:

1. A method for providing an annular strip between rotating andstationary portions of an elastic fluid machine comprising the steps of:

forming an annular groove having generally radially extending sidewallsin one of said portions of said machine,

inserting a corrugated strip of sheet material edgewise into said groovewith said strip extending beyond said groove,

deforming the strip to an annular shape,

shearing and deforming a portion of said strip, and

driving said sheared and deformed portion of said strip into at leastone of said sidewalls of said groove thereby securely fastening saidstrip in said groove.

2. The method as set forth in claim 1, wherein the steps of shearing anddeforming the strip and driving the sheared portion into at least onesidewall of the groove are performed simultaneously utilizing anassembling tool.

3. The method as set forth in claim 1 and further comprising the stepsof pressing the corrugated strip against the bottom of the groove,saidpressing step being performed prior to the step of shearing anddeforming.

4. The method as set forth in claim 1 and further comprising the step offorming the corrugated strip with flat surfaces which engage the sidesof the groove and shearing and deforming the strip in a plurality oflocations disposed within the flat surfaces.

5. The method as set forth in claim 4 and further com risin e ste offormin the c rru ated stri so as t8 hav l igameihts betweet the flatsurfaces and disposing said ligaments at an oblique angle with respectto the flat surfaces so as to accommodate the step of inserting thecorrugated strip into the groove.

6. A method for providing an annular seal between rotating andstationary portions of an elastic fluid machine comprising the steps of:

forming an annular seal having generally radially extending sidwalls inone of said portions of said machine,

inserting a rectilinear corrugated strip of sheet material edgewise insaid groove with said strip extending beyond said groove,

progressively deforming the strip to an annular shape,

shearing and deforming a portion of said strip, and

driving the shearing and deformed portion of said strip into at leastone of said sidewalls of said groove, thereby securely fastening saidstrip in said groove.

1. A method for providing an annular strip between rotating andstationary portions of an elastic fluid machine comprising the steps of:forming an annular groove having generally radially extending sidewallsin one of said portions of said machine, inserting a corrugated strip ofsheet material edgewise into said groove with said strip extendingbeyond said groove, deforming the strip to an annular shape, shearingand deforming a portion of said strip, and driving said sheared anddeformed portion of said strip into at least one of said sidewalls ofsaid groove thereby securely fastening said strip in said groove.
 2. Themethod as set forth in claim 1, wherein the steps of shearing anddeforming the strip and driving the sheared portion into at least onesidewall of the groove are performed simultaneously utilizing anassembling tool.
 3. The method as set forth in claim 1 and furthercomprising the steps of pressing the corrugated strip against the bottomof the groove, said pressing step being performed prior to the step ofshearing and deforming.
 4. The method as set forth in claim 1 andfurther comprising the step of forming the corrugated strip with flatsurfaces which engage the sides of the groove and shearing and deformingthe strip in a plurality of locations disposed within the flat surfaces.5. The method as set forth in claim 4 and further comprising the step offorming the corrugated strip so as to have ligaments between the flatsurfaces and disposing said ligaments at an oblique angle with respectto the flat surfaces so as to accommodate the step of inserting thecorrugated strip into the groove.
 6. A method for providing an annularseal between rotating and stationary portions of an elastic fluidmachine comprising the steps of: forming an annular seal havinggenerally radially extending sidwalls in one of said portions of saidmachine, inserting a rectilinear corrugated strip of sheet materialedgewise in said groove with said strip extending beyond said groove,progressively deforming the strip to an annular shape, shearing anddeforming a portion of said strip, and driving the shearing and deformedportion of said strip into at least one of said sidewalls of saidgroove, thereby securely fastening said strip in said groove.